Dog Age Calculator
This dog age calculator turns dog years into human years two ways: the chart the AVMA publishes for pet owners, and the 2020 DNA methylation study of Labrador retrievers. They disagree most in the early years.
Human years (AVMA chart)
- AVMA chart (medium-sized dog, 21 to 50 lb)
- 32 human years
- Epigenetic clock, Wang et al. 2020 (Labrador retrievers) 16 x ln(4) + 31 = 53.2.
- 53 human years
- Gap between the two methods
- 21 human years
- The old 7-to-1 rule
- 28 human years
| Dog's age | AVMA chart (21 to 50 lb) | Epigenetic clock (Labradors) |
|---|---|---|
| 1 year | 15 | 31 |
| 2 years | 24 | 42 |
| 3 years | 28 | 49 |
| 4 years | 32 | 53 |
| 5 years | 36 | 57 |
| 6 years | 42 | 60 |
| 7 years | 47 | 62 |
| 8 years | 51 | 64 |
| 9 years | 56 | 66 |
| 10 years | 60 | 68 |
| 11 years | 65 | 69 |
| 12 years | 69 | 71 |
| 13 years | 74 | 72 |
| 14 years | 78 | 73 |
| 15 years | 83 | 74 |
| 16 years | 87 | 75 |
How the Dog Age Calculator works
There is no single conversion from dog years to human years. There are published methods, and they give different answers because they measure different things. This dog age calculator shows two, each with a published source.
The first is the dog age chart the American Veterinary Medical Association publishes for pet owners. It counts a dog's first year as 15 human years and the second as 9 more, so a 2-year-old dog is 24. After that it adds 4 or 5 a year: 28 at 3, 32 at 4, 36 at 5, 42 at 6, then 47, 51, 56 and 60 at 10, reaching 87 at 16. Its footnote says the dog column is for a medium-sized dog of 21 to 50 lb and that weight and breed change the picture. Between two whole years the figure is read on a straight line between the chart's rows.
The second is a formula from a 2020 study in Cell Systems by Tina Wang, Trey Ideker and colleagues at the University of California, San Diego. They compared the DNA methylation in blood from 104 dogs, mostly Labrador retrievers aged 0.1 to 16 years, with the same marks in 320 people. Methylation changes with age in both species, so each dog could be matched to the people whose patterns it most resembled. The fit was human age = 16 x ln(dog age) + 31, with the natural logarithm of the dog's age in years. A 1-year-old dog comes out at 31, a 4-year-old at 53 and a 12-year-old at 71.
Put side by side, the two agree that dogs age fastest early and slow down later, and they disagree about how fast. For the default 4-year-old dog the chart gives 32 and the study gives 53, a gap of 21 years. By 12 the chart gives 69 and the study 71, nearly the same, and by 16 they part again at 87 and 75. The study's own paper calls the match closest at the infant and senior ends and only approximate in between. Its authors also say that breeds with very different lifespans could give different curves, and it was fitted on Labradors.
The old 7-to-1 rule is below both methods for a young dog and above both for an old one: 28 against 32 and 53 at 4, and 84 against 69 and 71 at 12.
Dog Age Calculator FAQ
How do I convert dog years to human years?
By the AVMA chart for a medium-sized dog, count 15 for the first year, 9 for the second, then 4 or 5 for each year after. A 4-year-old dog is 32. The 2020 epigenetic formula, 16 x ln(age) + 31, gives 53 for the same dog. Both are approximations.
Is one dog year really seven human years?
No. The 7-to-1 rule has no published basis. Both the AVMA chart and the 2020 Labrador study have dogs aging much faster than that in the first two years and more slowly afterward.
How old is a 1-year-old dog in human years?
15 on the AVMA chart and 31 by the 2020 epigenetic formula. The chart lines a 1-year-old up with a teenager; the study, which matched DNA methylation patterns, lines it up with a young adult.
Does the size of the dog change its age in human years?
The AVMA says weight and breed both influence aging, and its chart is for a medium-sized dog of 21 to 50 lb. The 2020 study was fitted on Labrador retrievers, and its authors say breeds with different lifespans could give a different curve.